An electro-optical imaging system will be developed into a portable hand- held device which will permit non-invasive, non-contact, real-time quantitative measurement of selected external parameters of pigmented lesions. These data will be displayed on a computer monitor, with an image of the lesion, immediately at the time of examination. The data will be used 1) to quantitatively follow long term changes, 2) to monitor short term response to therapy and 3) to build a data base useful in the differential diagnosis of lesions. Parameters to be measured will be lesion dimensions and height profile from which surface area and lesion volume will be calculated, lesion color and color of adjacent normal skin which will be used to calculate a colorimetric ratio, a measure of lesion surface roughness, and a measure of irregularity of the border of the lesion at the surface of the skin.